1. Technical Field
The present invention relates to a wiring board.
2. Related Art
In a package structure in which electronic components such as a semiconductor element are mounted in a wiring board, the other surface of the wiring board on the side opposite to one surface in which the electronic components are mounted is provided with a plurality of terminals for further connecting the package structure to terminals of an external board such as a motherboard and the like. Solder balls are provided on such terminals, and the wiring board and the external board are electrically connected to each other through the solder balls.
Japanese Unexamined Patent Publication No. 2006-066451 discloses the following configuration. A metal thin film such as nickel is formed on a base insulating layer, and a metal wiring (copper) made of a metal having a smaller ionization tendency than the ionization tendency of a metal for forming the metal thin film is formed on the metal thin film by an additive method. A cover insulating layer for coating the metal wiring is formed so that the metal wiring is partially exposed on the base insulating layer as a terminal portion, and a protective insulating layer is formed so as to be tightly adjacent to the side around the terminal portion exposed from the cover insulating layer. Thereby, it is possible to prevent the metal thin film from being corroded, and to achieve the improvement of adhesion between the metal wiring and the base insulating layer.
Japanese Unexamined Patent Publication No. 2002-158424 discloses a printed-circuit board in which a resist is applied spaced apart from a copper pattern provided on a substrate of the printed-circuit board, the exposed outer surface of the copper pattern is coated with Ni plating spaced apart from the resist, and the Ni-plated exposed outer surface is coated with Au plating.
Japanese Unexamined Patent Publication No. 561-264796 discloses a configuration in which nickel is provided between a conductive path and an aluminum terminal while the conductive path such as copper is formed on the aluminum terminal. Thereby, the difference of the ionization tendency between aluminum and copper is reduced by using nickel.